Very low frequency chopping operation of thermopile, which has relatively large aparture and time constant, has been studied and compared with dc mode. Amplification of very low frequency (0.1-0.3 Hz) is carried out with a digital lock-in system and a usual dc amplifier. Under chopping operation, apparent sensitivity falls with frequency increasing, but noise are also reduced, so detectivity at 0.2 Hz is 107 W-1cm Hz-1/2, which is 1.2 times greater than dc mode. Drift free operation is realised with dc drift component cut off. Linearity and uniformity of receiving area are similar to dc mode. Temperature coefficient of sensitivity has been improved and obtained value is-0.15%/°C at 19-29°C (about one half of that in dc mode).
The fundamental procedures involved with the two-monochromator method for determining the spectral radiance factors of fluorescent materials are described. Together with their measured results, the accuracy is described from a colorimetric point of view. The contents are as follow. (1) The procedures require a detector with accurately calibrated spectral sensitivity and a spectral irradiance standard lamp for determining the spectral fluorescent radiance factor (2) Based on the measured results of the reflected and the fluorescent radiance factor for several fluorescent materials, the colorimetric accuracy was confirmed by comparing the following sets of tristimulus values: the first ones calcul-ated from the results of the spectral radiance factors and the spectral power distributions of a tungsten halogen lamp and a Xe lamp which were determined seperately, and the second calculated from the total radiance factors obtained from the measurement under polichromatic illumination where the fluorescent materials are irradiated with the tungsten and the Xe lamp. The color differences between the tristimulus values in CIE 1976 L*u*v* color space are estimated to be less than 1.0 unit irrespective of the illuminant or the source.
Most architectural surface treatments do display near-uniform diffuse surface butmirrors, glass surfaces and highly glossy surfaces are used in many applications. Research of the influence of these specular surfaces on the luminous flux incident on work plane in a room which is bounded by diffuse and specular surfaces is required in a complete lighting design. Therefor, we have measured the total luminous flux incident on work plane in rectangular room having a specular reflected wall and have compared those results with the case of all the uniform diffuse surface. This paper provides the results of the experiment on the influence of specular wall surface. The results obtained are as follows, 1. The total luminous flux incident on work plane is significantly influenced by the specular wall surface at the lowest value of room index. 2. The indirect luminous flux incident on work plane from a specular wall surface increases remarkably compared with the uniform diffuse. 3. The difference of the total luminous flux between the specular wall surface and the uniform diffuse is remarkably affected by the first reflection from the wall surface.
This paper describes the characteristics of spectrometer and the measuring technique for spectral distribution in visible range using an Acoustooptic Tunable Filter (AOTF) employing a TeO2 crystal. The contents of the paper are summarized as follows: (1) The polarization characteristics of the diffracted lights of an AOTF are linear polarization.(2) The diffracted lights distribution is approximated to the Gaussian distribution.(3) The resolving power of the wavelength of the diffracted light is smaller than 3 nm.(4) The wavelength accuracy of the diffracted light is about 0. 002 nm/kHz.(5) The error of the spectral distribution is less than±1 % over the range of 380-500 nm and±0. 5% at the longer that 500 nm.(6) The wavelength and spectral transmittance of an AOTF can be controlled electronically without any mechanical means.
In the past, it was not simple to find the correlated colour temperature of a given light source, even though the chromaticity point on the xy-diagram is given, unless this point is on the locus of the full radiator or the light source has a spectral power distribution similar to the full radiator. It has been found, based on visual observations, that the iso-temperature lines plotted on the chromaticity diagram intersect arround a point at x0 =O. 329 and y0=O. 187 or u0=0. 286 and v0=0. 245. From this, the colour temperature may be given as a function of the slope (a) of the iso-temperature lines. The colour temperature of a given light source (x1, y1) can be found by calculating the slope (a) of the corresponding iso-temperature line which passes through the chromaticity point of the light source given as; a=(x1-x0) / (y1-y0). Based on the above, processing photo-electric signals activated in CIE tri-chromatic receivers, by means of electronic micro computers, a simple and reliable device has been developed. The device measures the correlated colour temperature of any light source directly and momentarily with an accuracy within 0. 3% in the range between 2500 K and 8000 K.
CIE-JIS method of color rendering specifications has a drawback, in that it cannot compare light sources with very different colors. The possibility is disscussed to remove the drawback by changing the uniform color space applied in the method. Apparent three attributes of test colors (eight high level and eight medium saturation) under various kinds of light sources were estimated directly by two observers. Their perceived chroma diagrams are compared with psychometric chroma diagrams calculated in accordance with the CIELUV and CIELAB spaces. The CIELAB space is much better than the CIELUV or CIELUW in simulating the apparent spacing of the test colors under various light sources. Effectiveness of several formulae for chromatic adaptation Correction was also tested. It is shown that only the nonlinear formula proposed by Nayatani et al. slightly improves the similarity of the CIELAB space to the percieved color space. The authors are going to propose the adoption of the CIELAB space even in the color rendering specification at the CIE TC-3. 2 meeting.
The relationship between illumination levels and physiological load has been studied by use of six steps of 1/4 log unit in the illuminance range from 100 to 1, 800lx. The other experimental conditions and methods were the same as those of the previous experiment. Heart beat and respiration were responsive to 1/4 log unit in illuminance. It was found that physiological load was minimum in the illuminance range 500 to 600lx, and increased as the illumination level was increased or decreased from this range. Psychologically, on the other hand, it was found that the illuminance range 800 to 900lx was the most desirable range, and desirability for illuminance decreased as the illumination level was increased or decreased from this range.
Experimental investigations of the lumen maintenance in dysprosium-thallium-sodium-cesium iodide arc lamps are described. Vertically burning 400 watt metal halide lamps were examined under the condition of continuous operation The lamps having low lumen maintenance were characterised as follows: (1) High reignition voltage at early stage of life, (2) appearance of mercuric iodide in the inner quartz tube, (3) deposition of silicon-dysprosium oxide compound on the coldest wall of the inner quartz tube after hundreds-hour operation, (4) deposition of silicon on the tip of the lower electrode after hundreds hour operation. Lamps with high reignition voltage contain impurity gas of hydrogen in the inner quartz tube with high partial pressure. It is concluded from the above mentioned results that the most important factor in lumen maintenance of the dysprosium-thallium-sodium-cesium iodide arc lamps is the chemical reaction between liquid dysprosium triiodide and quartz tube.
Efficiency improvement of a fluorescent lamp driving inverter for emergency lighting use is described. a separately excited one transistor inverter is applied to the 36% luminous flux system of a 20 watt lamp. A Darlington circuit was bridged with a coil to reduce the switching and driving losses in the transistor switch circuit. For effective use of battery energy, the input power to the lamp is kept constant by controlling the switching duty cycle against the change of source voltage. Two kinds of load circuits, direct current type and capacitance ballast type are studied. Consequently, an efficiency better than 83% and constant power characteristics are achieved in the prototype circuits.
This paper presents the energy saving effects in a building having automatically controlled lighting using daylight inside perimeter zone. We have developed a computer program that enables to calculate capital and energy cost of a building in order to estimate the energy saving effects, and calculated many cases under various conditions, such as four types of window ratio to wall (20%, 35%, 50%, 65%), three operation types of venetian blind, etc. Finally we estimated these energy saving effects by using a two-dimensional vector on a graph, on which the abscissa shows capital cost required and ordinate energy cost. By means of this vector on the graph, building owners can easily understand the energy saving effects of an automatically controlled lighting system using daylight.
As is well known, a reflected body varies in visual color according to illuminating and viewing conditions. Recently, interior decoration materials are in colorful use. Then, interior decoration materials vary in visual color according to illuminating and viewing conditions. We report results of some goniophotmetric color measurements on interior decoration materials. Change in color, when illuminating and viewing conditions are varied, have been investigated with the goniophotometric colorimeter. If we measure glossy color materials in the direction of specular reflection, the color of reflection light becomes similar to a light-sourse color on a chromaticity diagram. If we measure diffusible color materials, the color of reflection light does not vary on the chromaticity diagram. Color differences according to illuminating and viewing conditions are shown large in the glossy color materials. Color differences in the diffusible color materials does not vary under the illuminating and viewing conditions.